Plasma arc torches are widely used for high temperature processing (e.g., heating, cutting, gouging and marking) of materials. A plasma arc torch generally includes a torch head, an electrode mounted within the torch head, an emissive insert disposed within a bore of the electrode, a nozzle with a central exit orifice mounted within the torch head, a shield, electrical connections, passages for cooling, passages for arc control fluids (e.g., plasma gas) and a power supply. A swirl ring can be used to control fluid flow patterns in the plasma chamber formed between the electrode and the nozzle. In some torches, a retaining cap is used to maintain the nozzle and/or swirl ring in the plasma arc torch. In operation, the torch produces a plasma arc, which is a constricted jet of an ionized gas with high temperature and sufficient momentum to assist with removal of molten metal. Gases used in the torch can be non-reactive (e.g., argon or nitrogen), or reactive (e.g., oxygen or air).
There are certain conflicting demands on a plasma arc torch. One is to keep the torch diameter small so that it can easily access a wide variety of shapes, such as an I-beam channel. Another demand is to increase the amount of control and flexibility in the torch design to accommodate different processes. For example, consumable stack-ups for a 300 Amp process, a 130 Amp process and an 80 Amp process may look very different from one another. This may be because the processes need varying amount of copper in the nozzle to accommodate the heat load, such as more copper for higher-current nozzles. Further, a lower-current process may require a radial swirl injection flow whereas a higher-current process may require an axially injected swirl flow. A radial injection swirl has initial velocity components entering the plasma chamber in the tangential and radial directions. In this configuration, the axial flow direction, which is parallel to the cylindrical axis defined by the nozzle bore, is about zero. An axial swirl injection has initial velocity components in the tangential and axial directions. In this configuration, the initial radial component is about zero. In addition to the nature of the initial gas velocity, the location of the gas injection point into the plasma chamber is important and can change substantially from one design stack-up to another. Thus, there is a need for a torch design that can accommodate the varying flow control demands and other complexities for different operating currents, such as providing a single consumable component with flexible features that can accommodate these demands and complexities.